1. Field of the Invention
The invention relates to a method for improving body weight gain and increasing the efficiency of converting feed into body weight gain in animals, by feeding to animals an effective dose of antibodies against anti-nutritional factors commonly found in feedstuffs or produced by microorganisms present in the gastro-intestinal tract.
2. Discussion of the Background
In the animal industry, the feed accounts for 50% to 70% of the overall production cost. Therefore any improvement in the ability of the animal to convert feed into marketable products, e.g., animal body weight, can markedly improve profitability for the animal producer.
Various methods for improving feed conversion are known in the animal industry. One of the most common methods is adding sub-therapeutic levels of antibiotics to the feed, in order to improve animal performance. Antibiotics decrease the animal's exposure to bacterial infection and decrease the number of bacteria in the gastrointestinal tract, thereby allowing the animal to utilize nutrients more efficiently since the animal and the microflora are competing for the same nutrients. However continuous use of antibiotics as growth promoters causes several problems, including the introduction of drug residues in animal produce, promoting the growth of antibiotic resistant bacteria, and increasing the risk of environmental pollution. Due to the seriousness of these problems the use of antibiotics as growth promoters in the animal industry may soon be completely prohibited. The European Union has already banned the use of five different growth promoting antibiotics in animals raised for human consumption and others may follow. In the United States, three growth promoting antibiotics have been banned in recent years.
In order to replace growth-promoting antibiotics several new products have been developed. Enzymes such as phytase, protease and others have been used to assist in the digestion of certain nutrients, improving body weight gain in the animals. This improvement can be attributed to increased digestibility of the nutrients these enzymes help digest rather than to a decrease in gastrointestinal bacteria.
Other methods, such as Competitive Exclusion (CE) and probiotics, have been used to decrease the incidence of pathogenic organisms in animals. In case of CE, the animal is fed a high concentration of “helpful bacteria” that prevent foreign bacteria from colonizing the gastrointestinal tract. Although, CE has been successful in laboratory trials, field results have been inconsistent.
The use of antibodies to prevent certain infections in animals is known to enhance growth performance. Two possible mechanisms by which antibodies prevent infection have been proposed. According to the first mechanism, antibodies decrease the number of foreign bacteria in the gastrointestinal tract by binding to specific receptor sites, thus preventing the foreign bacteria from attaching to the intestine. According to the second mechanism, antibodies may decrease bacterial numbers by binding to specific receptors on the bacteria themselves thus preventing bacterial multiplication.
The effectiveness of avian antibodies in preventing bacterial infections in swine has been reported in several references. In vitro studies reported by Jungling et al. (J. Vet. Med 38:373-381, 1991) suggest that egg yolk antibodies are effective in decreasing the adhesion of enterotoxigenic E. coli onto isolated pig enterocytes.
Yokoyama et al. (Infect. Immunity 60:998-1007, 1992 and Am. J. Vet. Res. JY:867-872, 1993) and Erhard et al. (Berl. Munch. Tierarztl. Wschr. 106:383-387, 1993) disclose in vivo tests indicating that spray-dried egg yolk extracts containing antibodies against E. coli can prevent colibacillosis in newborn piglets and calves.
Kellner et al. (Jahrgang 49 January 94(1) 31-34, 1994) reported the results of studies demonstrating that spray-dried egg yolk extracts containing antibodies against E. coli administered to pigs decreased the number of days that pigs suffered from diarrhea
U.S. Pat. No. 5,741,489 to Pimentel discloses a method for increasing feed conversion efficiency in pigs and chickens by feeding the animals a diet containing chicken anti-urease antibodies. The reference, however, does not disclose a mixture of antibodies that inhibit several anti-nutritional factors in the animal feed.
The present invention provides an effective and safe method for enhancing body weight gain, feed conversion efficiency or both, in animals, by feeding the animals an antibody against anti-nutritional factors present in the gastrointestinal tract.